Renal 02: Development Of The Urinary System

Front 1

How many medullary pyramids are there in a kidney?

Back 1

6-18 conical medullary periods

Front 2

How many nephrons are there in a kidney?

Back 2

1.3-1.5 million nephrons / kidney

Front 3

Where is urine collected and drained?

Back 3

Calyces --> Renal Pelvis --> Ureter

Front 4

What is the precursor tissue for the urinary system?

Back 4

- Intermediate Mesoderm (IM) - component of the intraembryonic mesoderm (condensed mesenchyme cells)
- Endoderm (epithelium of bladder and urethra)

Front 5

Where is the Intermediate Mesoderm (IM) located?

Back 5

In between the medial paraxial mesoderm and the laterally positioned lateral plate mesoderm

Front 6

When does the Intermediate Mesoderm (IM) separate from the medially located Paraxial Mesoderm?

Back 6

During folding of the embryo in the horizontal (transverse) plane

Front 7

What kidney and gonad precursor forms from the Intermediate Mesoderm?

Back 7

Nephrogenic Ridge or Cord - distinct ridge on posterior wall of coelom

Front 8

What forms from the Nephrogenic Ridge / Cord? Where is it?

Back 8

- Later called the Urogenital (UG) Ridge
- Becomes Kidney and Gonad precursors
- Distinct ridge on posterior wall of coelom

Front 9

What are the implications of urinary and gonadal precursors originate from the same tissues?

Back 9

If you have anomalies in the urinary system you will also probably have anomalies in the genital system (and vice versa)

Front 10

What Urinary System structures are derived from Intermediate Mesoderm?

Back 10

- Kidney
- Calyces
- Renal Pelvis
- Ureter

- Gonads
- Genital Ducts

Front 11

What Urinary System structures are derived from Endoderm?

Back 11

Epithelial lining of urinary bladder and urethra

Front 12

What Urinary System structures are derived from Splanchnic Mesoderm?

Back 12

Smooth muscle and CT in walls of the components of the urinary system

Front 13

What mediates the specification of kidney-forming ability to the Intermediate Mesoderm?

Back 13

Signals from the Paraxial Mesoderm: transcription factors Pax2, Pax8, Lim1

Front 14

What happens if you knock out of these transcription factors: Pax2, Pax8, and Lim1?

Back 14

You would have abnormal kidney formation

Front 15

What kidney structures appear along the nephrogenic ridge?

Back 15

- Mesonephric Kidney
- Metanephric Kidney

Front 16

Where does the Mesonephric Kidney form?

Back 16

- Within the Nephrogenic Ridge
- Thoracolumbar Region of embryo
("middle kidney")

Front 17

When is the Mesonephric Kidney functional?

Back 17

Transient structure that is functional from weeks 6-12

Front 18

What are the two components of the Mesonephric Kidney?

Back 18

- Mesonephric Duct
- Mesonephric Tubules

Front 19

What does the Mesonephric Duct begin as? What happens to it?

Back 19

- Solid cord of cells that extend caudally through the nephrogenic ridge on each side of embryo
- Lumen forms within duct
- Duct fuses w/ the cloaca (dilated, caudal end of primitive hindgut)

Front 20

What does the lumen of the Mesonephric Duct fuse with? What is the purpose of this?

Back 20

- Fuses with the Cloaca (dilated, caudal end of primitive hindgut)
- Serves as a transient common outlet for the UG and GI systems

Front 21

What does the Mesonephric Tubule begin as? What happens to it?

Back 21

- S-shaped structure that forms at regular intervals along the nephrogenic cord
- One end is associated with a tuft of capillaries
- Differentiation occurs in cranial to caudal direction along nephrogenic ridge (inductive signals from mesonephric duct)

Front 22

What are Mesonephric Tubules essentially?

Back 22

Immature Nephrons (simple form of the mature kidney tubules)

Front 23

What induces tubule formation of the mesonephric tubules?

Back 23

Inductive signals from the Mesonephric Duct

Front 24

How many mesonephric tubules form along the ridge in each kidney? How many remain in the functioning mesonephros?

Back 24

- 40 tubules originally (not all tubules are present at the same time, many of the cranial tubules disappear before the caudal tubules form)
- 20 remain in functioning mesonephros

Front 25

What is the fate of the Mesonephric Ducts?

Back 25

- The ducts distal to the metanephric diverticulum exhibit sexual dimorphism
- Males: forms Vas Deferens, Epididymis, Seminal Vesicles, Ejaculatory Ducts
- Females: atrophies (remnant structures in the uterine mesentery)

Front 26

What is the fate of the Mesonephric Tubules?

Back 26

- Tubules also exhibit sexual dimorphism
- Males: subset of tubules form efferent ductules
- Females: atrophies (remnant structures in the ovarian mesentery)

Front 27

What parts of the Mesonephric Kidney remain in males? What does it form?

Back 27

- Mesonephric Ducts (distal to the metanephric diverticulum) form Vas Deferens, Epididymis, Seminal Vesicles, Ejaculatory Ducts
- Mesonephric Tubules form subset of tubules form efferent ductules

Front 28

What parts of the Mesonephric Kidney remain in females? What does it form?

Back 28

- Mesonephric Ducts atrophy (remnant structures in the uterine mesentery)
- Mesonephric Tubules atrophy (remnant structures in the ovarian mesentery)

Front 29

What structure is the precursor to the permanent kidney? Where is it located?

Back 29

Metanephros (Metanephric Kidney) - located in the pelvic region of the embryo

Front 30

What is the original location of the Mesonephros and the Metanephros?

Back 30

- Mesonephros: throacolumbar region of embryo
- Metanephros: pelvic region of embryo

Front 31

What does the Metanephric Kidney form from?

Back 31

Caudal aspect of the nephrogenic cord

Front 32

What are the precursors of the Metanephric Kidney? What tissues are they derived from?

Back 32

- Metanephric Diverticulum (Ureteric Bud) - derivative of mesonephric duct
- Metanephrogenic Mesenchyme (Metanephric Blastema)
- Both derived from Intermediate Mesoderm

Front 33

What does the Metanephric Diverticulum begin as? What happens to it?

Back 33

- Derivative of the mesonephric duct (intermediate mesoderm)
- Buds off of the mesonephric duct as it bends medially to contact the epithelium of the cloaca
- Forms the Ampulla d/t inductive signals from metanephric mesenchyme

Front 34

What does the Metanephric Mesenchyme begin as?

Back 34

Accumulation of mesenchyme at the caudal end of the nephrogenic ridge

Front 35

How do the precursors of the Metanephric Kidney (diverticulum and mesenchyme) interact?

Back 35

- Inductive interactions between these precursors results in formation of nephrons and a collecting system of the kidney
- Reciprocal interactions mediated by growth factors, secreted factors, and ECM molecules

Front 36

What structure forms the Ampulla? How? Function?

Back 36

- Inductive signals cause distal end of the metanephric diverticulum to dilate and form the ampulla
- Primary source of inductive signals for nephron formation

Front 37

What can happen if the inductive signals between the metanephric diverticulum and the metanephric mesenchyme are altered or absent?

Back 37

Renal Agenesis: absence of the kidney

Front 38

What happens in Renal Agenesis?

Back 38

- Inductive signals between the metanephric diverticulum and the metanephric mesenchyme are altered or absent
- Absence of the kidney(s)

Front 39

What are the types of Renal Agenesis? How common are they?

Back 39

- Unilateral (1 / 600-1000) - usually on L side
- Bilateral (1 / 2000)

Front 40

What are the features of Unilateral Renal Agenesis?

Back 40

- 1 / 600-1000
- Usually asymptomatic
- 30-40% of children have associated anomalies in other organs
- Usually on L side
- Can be associated w/ a single umbilical artery

Front 41

What are the features of Bilateral Renal Agenesis?

Back 41

- 1 / 2000
- Incompatible w/ extra-uterine life
- Associated with Oligohydramnios and Pulmonary Hypoplasia
- Compression of the face d/t decreased amniotic fluid → Potter's facial sequence
- Associated w/ GI, heart, UG, and nervous system anomalies

Front 42

What are the abnormalities associated with the amount of Amniotic Fluid?

Back 42

- Oligohydramnios: too little amniotic fluid
- Polyhydramnios: excessive amniotic fluid

Front 43

What can cause Oligohydramnios?

Back 43

Defect of urinary output (urine = amniotic fluid)
- Renal agenesis (bilateral)
- Polycystic kidney disease
- Urethral obstruction

Chronic amniotic leak

Front 44

What are the features of children born in association w/ Oligohydramnios?

Back 44

1. Facial anomalies (Potter's Facies: low set ears, recessed chin, flat nose, widened subcanthal fold)
2. Limb deformities (d/t abnormal positioning)
3. Pulmonary Hypoplasia
4. Fetal growth restriction

Front 45

What can cause Polyhydramnios?

Back 45

Most common:
- Multiple gestations

Associated with:
- Maternal diabetes mellitus

Interference with fetus swallowing amniotic fluid:
- Anencephaly
- Esophageal or duodenal atresia

Front 46

What is the function of Amniotic fluid?

Back 46

Physical Roles:
- Shock absorber
- Enables fetus to move about freely, enhancing muscular development (especially limbs)
- Maintains fetal body temperature
- Essential for normal lung development
- Barrier to infection

Nutritive Role:
- Source of nutrients early in development that can diffuse into embryo

Excretory Role:
- Assists in homeostasis by maintaining fluid and electrolytes (especially prior to keratinization of skin)

Front 47

What are the physical roles of the Amniotic Fluid?

Back 47

- Shock absorber
- Enables fetus to move about freely, enhancing muscular development (especially limbs)
- Maintains fetal body temperature
- Essential for normal lung development
- Barrier to infection

Front 48

What are the nutritive roles of the Amniotic Fluid?

Back 48

Source of nutrients early in development that can diffuse into embryo

Front 49

What are the excretory roles of the Amniotic Fluid?

Back 49

Assists in homeostasis by maintaining fluid and electrolytes (especially prior to keratinization of skin)

Front 50

What is the source of amniotic fluid?

Back 50

- First 10 weeks: Amnion - interstitial fluid diffuses across the amniochorionic membrane from decidua parietalis (lining of uterus not involved in placenta formation)
- After 10 weeks: Fetus - swallows and excretes it into urine (also from tracheobronchial secretions)

Front 51

What helps direct the definitive arrangement of nephrons and collecting ducts found in the kidney?

Back 51

Ampulla (expanded terminal end of the metanephric diverticulum)

Front 52

When do nephrons stop forming?

Back 52

When the ampullae disappear (~32 weeks)

Front 53

How do kidneys grow during childhood? Are new nephrons formed?

Back 53

- Growth of kidney during childhood is d/t elongation of nephron tubules
- No new nephrons are formed because the ampullae are gone

Front 54

How do the nephrons in mesonephros compare to metanephros?

Back 54

Metanephros nephrons are much more complex and are also the adult nephrons

Front 55

How do nephrons form?

Back 55

1. Signals from Metanephric Mesenchyme (MM) - GDNF, RA - induce formation of Metanephric Diverticulum (MD) - receptors for GDNF
2. MD branches
3. Tips of MD expand (= ampulla) - key signaling center for nephron induction
4. Signals from ampulla direct arrangement of nephrons and collecting ducts
5. MD signals (Fgf2, Bmp7) prevent MM cell apoptosis and induces aggregation around the ampulla = COMPACTION
6. Mass of MM transforms into an epithelium bounded cavity = VESICLE FORMATION
7. Epithelial vesicle fuses w/ ampulla = FUSION OF VESICLE W/ URETERIC BUD
8. Elongates to form an S-shaped tubule = S-SHAPED TUBULE FORMATION

Front 56

What happens after ampulla formation?

Back 56

Metanephric mesenchyme condenses around the ampulla = COMPACTION

Front 57

What happens after metanephric mesenchyme condenses around the ampulla (Compaction)?

Back 57

Mass of MM transforms into an epithelium bounded cavity = VESICLE FORMATION

Front 58

What happens after the vesicle formation?

Back 58

Epithelial-lined vesicle fuses w/ ampulla = FUSION OF VESICLE W/ URETERIC BUD

Front 59

What happens after the epithelial-lined vesicle fuses w/ ampulla?

Back 59

Elongates to form an S-shaped tubule = S-SHAPED TUBULE FORMATION

Front 60

What results in the formation of the mature nephron?

Back 60

Elongation and differentiation of the parts of the S-shaped tubule

Front 61

What do the proximal, middle, and distal portions of the S-shaped tubule become in the adult nephron?

Back 61

- Proximal: Distal Tubule (convoluted and straight) and Loop of Henle
- Middle: Proximal Tubule (convoluted and straight)
- Distal: Double walled capsule of the Renal Corpuscle (Bowman's Capsule), invaded by capillary plexus that forms glomerulus

Front 62

What part of the S-shaped tubule forms the Distal Tubule?

Back 62

Proximal section of S-shaped Tubule

Front 63

What part of the S-shaped tubule forms the Loop of Henle?

Back 63

Proximal section of S-shaped Tubule

Front 64

What part of the S-shaped tubule forms the Proximal Tubules?

Back 64

Middle section of S-shaped Tubule

Front 65

What part of the S-shaped tubule forms the Renal Corpuscle?

Back 65

Distal section of S-shaped Tubule

Front 66

What is the origin of "vascular sprouts"? What do "vascular sprouts" become?

Back 66

- They come from intersegmental arteries (located between somites)
- Remodel to form the blood supply to the kidney

Front 67

How do "vascular sprouts" become the blood supply of the kidney?

Back 67

- Inductive signaling that is directing nephron formation causes the vascular sprouts to grow towards the forming kidney
- Only induced metanephrogenic mesenchyme is competent to secrete angiogenic growth factors (VEGF) that stimulate vascular sprouting

Front 68

What structures does branching of the Metanephric Diverticulum form? Which branching "generations"?

Back 68

- Collecting ducts (>6th generation branches)
- Calyces (3rd-6th generation branches)
- Renal pelvis (3rd-6th generation branches)
- Ureter (3rd-6th generation branches)

Front 69

What are the features of branching in the Metanephric Diverticulum?

Back 69

- Early generations branch and have little growth or elongation before next branching event occurs
- Initial branches are short
- Polar end branches grow faster than central branches

Front 70

Why is the kidney, "kidney-shaped"?

Back 70

Polar (end branches) grow faster than the central branches

Front 71

Can you see the individual kidney lobes?

Back 71

- Visible externally in embryo and fetus
- As kidney grows during childhood, lobes usually merge and become indistinct

Front 72

What are kidney / renal lobes?

Back 72

Pyramidal-shaped organization of nephrons and collecting ducts

Front 73

Are anomalies of the urinary system common? Clinically significant?

Back 73

- They are common (3-4% of newborns have some variation or anomaly)
- But not always clinically significant

Front 74

What are some anomalies of kidney size, number, or histological organization?

Back 74

- Hypoplastic kidneys - small, but normal (d/t abnormal development)
- Duplications - all or part of kidney or ureter
- Dysplastic kidney development - cysts or primitive looking tissue arrangement

Front 75

What is the most common cause of multi-cystic kidneys?

Back 75

Dysplastic kidney development

Front 76

What is the outcome of bilateral dysplastic kidney development?

Back 76

- Commonly causes multi-cystic kidneys
- Fatal post-natally w/o some sort of intervention like dialysis

Front 77

What is the term for a kidney in an abnormal location? On what side is this more common? How common in general?

Back 77

Ectopic Kidney - more common on L side (1/800 live births)

Front 78

In what location does a normal kidney grow? In what locations do Ectopic Kidneys grow?

Back 78

- Normal: metanephric kidney develops in pelvis and then ascends into abdomen (because of differential growth of the embryonic body)

- Ectopic: Pelvic (60%) or Lumbar region (d/t failed or incomplete ascent to normal position in abdomen)

Front 79

What is often the reason for the presence of accessory renal arteries? How common is this?

Back 79

Ascent of kidney from pelvis to abdomen (30%)

Front 80

How common is a "horseshoe kidney"? What causes this?

Back 80

- 1 / 425-600 live births
- Often occurs because of fusion of the caudal poles of the kidney
- Ascent to normal position is blocked by inferior mesenteric artery
- May be associated with additional anomalies

Front 81

What happens in "Crossed Renal Ectopia"?

Back 81

- Both kidneys are located on the same side of the body
- They may fuse or remain unfused

Front 82

What is the term for both kidneys being on the same side of the body?

Back 82

Crossed Renal Ectopia

Front 83

What are the possible causes (differential diagnosis) of a R flank mass in an infant?

Back 83

- Hydronephrosis (obstruction of urinary tract)
- Cystic kidney disease (polycystic or multicystic dysplastic)
- Renal tumor (rare)

Front 84

Does multicystic dysplastic kidney disease affect one or both kidneys? Polycystic?

Back 84

- Multicystic - usually unilateral (bilateral is rare and fatal)
- Polycystic - bilateral

Front 85

What are the gross features of Multicystic Dysplastic Kidney Disease?

Back 85

- Multiple cysts of varying sizes on one of the kidneys
- Contralateral (normal) kidney hypertrophies to compensate for lost functional kidney mass

Front 86

What are the pathologic features of Multicystic Dysplastic Kidney Disease?

Back 86

- Primitive ductules and cartilage
- Atretic ureter (abnormally closed or absent)

Front 87

What other abnormalities are associated with Multicystic Dysplastic Kidney Disease?

Back 87

- 28% have vesicoureteral reflux in contralateral kidney (movement of urine from bladder → ureters → kidney)
- Hypertension (potential complication)

Front 88

What happens to the diseased kidney in Multicystic Dysplastic Kidney Disease? How do you treat this?

Back 88

- Usually regresses on its own
- If it does not regress by the time they are a toddler, a nephrectomy is indicated

Front 89

Is Multicystic Dysplastic Kidney Disease caused by a genetic abnormality?

Back 89

No, non-genetic

Front 90

What are the types of congenital polycystic kidney disease? How common are they?

Back 90

- Autosomal Recessive Polycystic Kidney Disease (ARPKD) - 1 / 6000-14,000 live births
- Autosomal Dominant Polycystic Kidney Disease (ADPKD) - 1 / 1000 live births

Front 91

What are the morphological features of Autosomal Recessive Polycystic Kidney Disease?

Back 91

- Kidney contains enlarged cortical cysts
- 90% of collecting tubules are dilated
- Normal reniform (kidney-bean) shape persists

Front 92

What are the outcomes of Autosomal Recessive Polycystic Kidney Disease depending on the age of onset?

Back 92

- Manifested in newborns (most common): fatal
- Manifested in infants or children: develop liver problems, HTN, CHF
- Manifested in adults: develop liver fibrosis and portal HTN

Front 93

What are the morphological features of Autosomal Dominant Polycystic Kidney Disease?

Back 93

- Cysts are located in cortex and medulla
- Bilateral enlarged kidneys

Front 94

When do patients become symptomatic from Autosomal Dominant Polycystic Kidney Disease?

Back 94

30s-50s (but can occur in children)

Front 95

What mutations cause Autosomal Dominant Polycystic Kidney Disease?

Back 95

Mutations on two genes on chromosome 16: PKD1 and PKD2

Front 96

What happens if someone has mutations in PKD1 or PKD2 on chromosome 16?

Back 96

- Loss of function of the primary cilium on renal tubular epithelial cells
- These proteins (polycystin 1 and 2) may be part of the signaling pathway that regulates renal tubular size and growth

Front 97

What are the outcomes of Autosomal Dominant Polycystic Kidney Disease?

Back 97

- 50% develop HTN
- 33% develop berry aneurysms on their internal carotid arteries
- 80% develop intestinal diverticulosis

Front 98

What kind of kidney neoplasm is common in children? What gene is involved? How common?

Back 98

- Nephroblastoma (Wilm's Tumor)
- Wilm's tumor gene, Wt-1, is on chromosome 11p1
- 1 / 15,000 live births

Front 99

What part of the kidney does Nephroblastoma (Wilm's Tumor) affect?

Back 99

- Early onset occurs in medulla
- Later progresses to cortex

Front 100

What is Nephroblastoma (Wilm's Tumor) associated with?

Back 100

- Horseshoe kidney
- May be associated with other anomalies and certain syndromes

Front 101

What causes Hydronephrosis? What does it result in?

Back 101

- Caused by obstruction of urinary flow, usually at the ureter-pelvic junction (UPJ)
- Leads to distention of the renal pelvis and calyces

Front 102

What is the most frequent cause of a neonatal abdominal mass?

Back 102

Hydronephrosis
- Caused by obstruction of urinary flow, usually at the ureter-pelvic junction (UPJ)
- Leads to distention of the renal pelvis and calyces

Front 103

What can enhance an obstruction in the urinary tract?

Back 103

- Diuresis (increased water excretion)
- Eg, EtOH

Front 104

What symptoms in an infant would make you believe they had a Utero-Pelvic Junction obstruction (Hydronephrosis)?

Back 104

- Flank mass
- UTI
- Failure to thrive
- Sepsis

Front 105

What symptoms in an older child or adult would make you believe they had a Utero-Pelvic Junction obstruction (Hydronephrosis)?

Back 105

- Flank pain
- Colicky pain
- UTI
- Hematuria

Front 106

How can you diagnose a Utero-Pelvic Junction obstruction (Hydronephrosis)?

Back 106

- Ultrasound (anatomy)
- Renal scan
- IV pyelogram (functional study)

Front 107

How does the Cloaca get subdivided?

Back 107

Urorectal Septum (wedge of mesoderm located between alantois and hindgut)

Front 108

What is the function of the Urorectal Septum?

Back 108

- Subdivides the cloaca into UG Sinus (ventral) and Anorectal Canal (dorsal)
- Expands ventrally to fuse w/ the cloacal membrane (driven by embryo growth and caudal folding in sagittal plane)

Front 109

What forms the perineal body?

Back 109

Area between the Urorectal Septum and the Cloacal Membrane

Front 110

What separates the cloaca from communicating with the amniotic cavity?

Back 110

Cloacal Membrane - fusion of ectoderm and endoderm that covers the ventral surface of the cloaca

Front 111

What does the Cloacal Membrane cover?

Back 111

- Covers the ventral surface of the cloaca
- Extends from the Allantoic Stalk to the Tailbud

Front 112

When does the Cloacal Membrane rupture? Why?

Back 112

- Ruptures around day 49
- Caused by apoptosis and pressure from urine in Amniotic Cavity
- Results in distinct openings for the UG tract and the GI tract

Front 113

What are the subdivisions of the UG Sinus?

Back 113

- Cranial / Vesicle part (aka vesicourethral canal)
- Middle / Pelvic part
- Caudal / Phallic part

(Sometimes pelvic and phallic parts are grouped together as the definitive UG sinus)

Front 114

What part of the UG sinus do the Mesonehpric Ducts open into?

Back 114

Cranial / Vesicle part (aka vesicourethral canal)

Front 115

What happens to the pelvic and phallic parts of the UG sinus?

Back 115

- Pelvic (middle) part narrows
- Phallic (caudal) part flattens and is pulled ventrally as the genital tubercle elongates

Front 116

What develops from the cranial part of the vesicle of the UG sinus?

Back 116

- Urinary bladder
- Part of the urethra

Front 117

What is the vesicle part of the UG sinus continuous with?

Back 117

Cranially it is continuous with the regressing allantois

Front 118

What is the cranial extension of the forming urinary bladder called?

Back 118

Urachus

Front 119

What is the urachus?

Back 119

Cranial extension of the forming urinary bladder

Front 120

Eventually, what happens to the urachus and alantois?

Back 120

- Narrow to a fibrous cord called the Median Umbilical Ligament
- Inner surface of the ventral wall of the abdomen
- Ligament tracks from the apex or cranial surface of the urinary bladder to the umbilicus

Front 121

What are the origins of the components of the urinary bladder?

Back 121

- Cranial part of UG Sinus (forms bladder and part of urethra) - intermediate mesoderm
- Lining derived from endoderm
- Smooth muscle and CT in wall derived from surrounding splanchnic mesoderm

Front 122

What forms the ureters?

Back 122

Metanephric Diverticula (Ureteric Bud)

Front 123

What opens into the vesicle part of the UG sinus?

Back 123

- Caudal end of the mesonephric ducts
- Metanephric diverticula (forming ureters)

Front 124

What happens to the mesonephric ducts in relation to the urinary bladder?

Back 124

- Ends exstrophy (expand and flatten)
- Greater superiorly, causes the ureters to open into the forming urinary bladder
- Distal end of ducts appear as if they are moving caudally and open into pelvic portion of UG sinus
- They also move closer together

Front 125

Where are the openings of the ureters in relation to the mesonephric ducts?

Back 125

Lateral and superior to the mesonephric ducts

Front 126

What is the thickened triangular area of the posterior bladder that is bounded by the openings of the ureters and urethra?

Back 126

Trigone of Urinary Bladder

Front 127

What is the Trigone derived from?

Back 127

- Extrophied mesonephric duct distal to the metanephric diverticulum (mesodermal origin)
- Internally the trigone is overgrown by endoderm

Front 128

What do the derivatives of the mesonephric ducts in males drain into?

Back 128

Form components of the male reproductive system that empty into the prostatic urethra

Front 129

What happens to the bladder after birth?

Back 129

Bladder descends and drags the cord-like median umbilical ligament (derived from urachus and alantois) with it

Front 130

What does the caudal portion of the vesicle part of the UG sinus form?

Back 130

Contributes to the forming urethra

Front 131

How is the urethral primordium sexually dimorphic?

Back 131

- Males: only the proximal part of the prostatic urethra is formed from the vesicular part of the UG sinus
- Females: most of the urethra is derived from the vesicular part of the UG sinus

Front 132

What forms from the pelvic part of the UG sinus?

Back 132

- Males: epithelium of Distal Prostatic and Membranous Urethra
- Females: epithelium of lower half of vagina

Front 133

What forms from the phallic part of the UG sinus?

Back 133

- Males: epithelium of Penile Urethra
- Females: epithelium of the vestibule

Front 134

What do the portions of the UG sinus form in females?

Back 134

- Vesical: most of the urethra
- Pelvic: epithelium of lower half of vagina
- Phallic: epithelium of vestibule

Front 135

What do the portions of the UG sinus form in males?

Back 135

- Vesical: epithelium of Proximal Prostatic Urethra
- Pelvic: epithelium of Distal Prostatic Urethra and Membranous Urethra
- Phallic: epithelium of Penile Urethra

Front 136

What are the types of anomalies that are associated with the Urinary Bladder?

Back 136

- Urachal anomalies
- Exstrophy of the bladder

Front 137

What are the Urachal Anomalies of the Urinary Bladder? Cause?

Back 137

- Urachal cysts (C)
- Vesical diverticulum (B)
- Vesico-umbilical fistula (A)

- Failure of regression of the urachus and alantois

Front 138

What kind of anomaly is a Urachal Cyst? What causes them?

Back 138

- Type of urachal anomaly of the urinary bladder
- Derived from epithelial lining of the urachus
- Caused by failure of regression of urachus
(C)

Front 139

What kind of anomaly is a Vesical Diverticulum? What causes them?

Back 139

- Type of urachal anomaly of the urinary bladder
- Communication between bladder and a remnant of the urachus (B)
- Caused by failure of regression of urachus

Front 140

What kind of anomaly is a Vesico-Umbilical Fistula (aka Patent Urachus)? What causes them?

Back 140

- Type of urachal anomaly of the urinary bladder
- Communication of bladder w/ the umbilicus d/t patency of the urachus and alantois; with this condition urine at umbilicus is possible (A)
- Caused by failure of regression of urachus

Front 141

What does the term exstrophy mean?

Back 141

Eversion of a hollow organ so that its epithelial lining is exposed to the surface of the body or the inside of an organ

Front 142

What happens in Exstrophy of the Urinary Bladder? What is it associated with?

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- Mucosal lining of the posterior bladder wall is exposed on the ventral abdominal wall
- Males: often associated w/ Epispadias (dorsal opening of penile urethra)
- Females: often associated w/ a shortened vagina and a bifid clitoris
- Also associated w/ UG and skeletal anomalies (separation of pubic bones)
- 1 / 30,000 - 50,000 live births and 3.5x more common in males

Front 143

What causes Bladder Exstrophy?

Back 143

Failure of medial mesenchymal migration

Front 144

What happens in Exstrophy of the Cloaca?

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- More severe form of Exstrophy of Urinary Bladder
- Also includes Omphalocele (abdominal organs protrude into umbilical cord), impeforate anus, and spinal anomalies
- 1 / 250,000 births

Front 145

What is Epispadias? What is it associated with?

Back 145

Dorsal opening of penile urethra - associated with males with Exstrophy of the bladder

Front 146

How should Bladder Exstrophy be treated? What are the complications?

Back 146

- Surgery performed shortly after birth
- Babies hospitalized 10-14 days
- Incontinence is a major long term issue; upper tracts at risk after repair

Front 147

What happens in Primary Ureteral Reflux? Cause?

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- Backing up of urine from bladder into ureter and kidney
- Occurs when ureter enters bladder abnormally in a more lateralized position
- Leads to loss of tunneling of ureter within wall of bladder
- May be related to abnormal location of metanephric diverticulum (ureteral bud) coming off of mesonephric duct

Front 148

What are the complications of Primary Ureteral Reflux?

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- Allows bacteria to have ascending access to kidneys, and thus is a risk for developing pyelonephritis (kidney infection)
- Also may cause subsequent atrophy of the kidney

Front 149

What is associated with a higher grade of ureteral reflux?

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- Greater risk for scarring
- More abnormal anatomy
- Spontaneous resolution less likely
- Surgical intervention may be necessary

Front 150

How should you treat primary ureteral reflux?

Back 150

- Antibiotic prophylaxis and/or
- Surgical repair

Front 151

What are the anomalies associated with the ureter

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- Duplications
- Ectopic Ureter
- Megaureter
- Ureterocele

Front 152

What happens in a Ureter Duplication?

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- All or part of ureter may be duplicated
- Most ar partial, with each ureter draining a separate pelvic coordinating system and then joining distally before entering bladder
- Can be unilateral or bilateral

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What happens in an Ectopic Ureter?

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- When ureter duplication is complete, one may empty into vagina, urethra, uterus, seminal vesicles, verumontanem (median elevation of prostatic urethra), or ejaculatory ducts
- Ureter than inserts ectopically is always the one that drains the more superior part of the kidney
- If the ureter does not have a sphincter, it may lead to continuous dribbling

Front 154

When there is a complete duplication of a ureter, what part of the kidney does it attach to? How do you know which is the ectopic ureter?

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- It drains more superior part of kidney
- It is inserted into vagina, urethra, seminal vesicles, verumontanem, or ejaculatory ducts

Front 155

What happens in a Megaureter? Cause?

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- Obstructred and enlarged ureter w/ a normal insertion site and orifice
- Distal ureter is adynamic - functionally obstructed d/t abnormal orientation of smooth muscle in wall

Front 156

What happens in Ureterocele?

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- Dilation of terminal ureter as it enters bladder d/t small ureter orifice
- More common in females and often associated w/ ureter duplication
- Often causes obstruction of affected ureter

Front 157

What kind of anomaly causes a ureter to drain into the vagina, uterus, seminal vesicles, verumontanem, or ejaculatory ducts?

Back 157

Ectopic Ureter

Front 158

What kind of anomaly is caused by an abnormal orientation of the smooth muscle in the wall of the ureter? Outcome?

Back 158

Megaureter - leads to obstructed and enlarged ureter w/ a normal insertion site and orifice

Front 159

What kind of anomaly is associated w/ a dilation of the terminal ureter as it enters the bladder d/t a small ureter orifice?

Back 159

Ureterocele

Front 160

What are the anomalies associated with the Urethra?

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- Agenesis / Atresia
- Posterior Urethral Valves

Front 161

What happens if there is agenesis or atresia of the urethra? Who more commonly gets it?

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- Obstruction of urine flow
- Development of prune belly (wrinkling of abdominal wall) d/t atresia of ventral abdominal wall muscles
- More common in males

Front 162

What are posterior urethral valves?

Back 162

- Urethral anomaly
- Tissue folds of posterior urethra mucosa that act like valves and obstruct the urethra

Front 163

What happens if there are posterior urethral valves? Who can get this?

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- Most common cause of uropathy leading to renal failure in children (irreversible renal dysplasia)
- Tissue folds of posterior urethra mucosa act like valves and obstructs the urethra
- Only found in MALES (1/5000 live births)

Front 164

What is a common cause of renal failure in boys?

Back 164

Posterior Urethral Valves - tissue folds of posterior urethral mucosa that act like valves and obstruct the urethra